zmzmrx8

Why isn't anyone porting the throttle body or designing a new one?

ironmedic

im not sure about rotaries but with my stang, we cannot port our throttle bodies due to a special coating on the inside of it to protect it from heat/corrosion, etc...

im sure later on they will have new throttle bodies for sale. personally i believe they dont do jack for your car unless the rest of the manifold is ported or its an aftermarket type.

alex

cleaning and polishing only got me throttle response from the pedal .. I don't think I got hP out of it or it was minimal. This was off a 93 300ZX TT ..so, I'm comparing apples to oranges

edit: sorry, I meant clean and polishing the throttles not porting .. I was thinking of something else. :D

Ajax

From what we saw at racing beat, the intake seemed very purposely sized for the throttle body they used. Yes, a larger throttle body would mean you could use a larger intake and flow more air, but there didnt seem to be much room to really bore out on the throttle body.
I'm sure someone will do it eventually.

shelleys_man_06

It's not really a good modification for a larger bore throttle body. You're not going to expect many gains. I agree with Ajax. The throttle body is built for the intake manifold. Changing it may actually hurt performance.

zoom44

wouldnt hurt i think but since the intake manifold can only take the amount of air that its getting from the stock throttle body it wouldnt gain you anything. i know i was looking into this awhile back. the throttle body is not a bottleneck now.

reddragonmd

big bore throttle bodies just give you a better throttle response, they dont do much in terms of HP. Of course im speaking of 5 years of vw vr6 motor tuning, not rotary

Ajax

well.. let's put it this way..

assume the end of the throttle body is an extension of the intake.. If you make it wider than the intake, you increase the volume of air it can hold. If you fill that volume at the same rate that you did previously, you have less air pressure going into the engine. Assuming the engine can actually use more air, then the larger volume of air in that throttle body would probably give slight gains and you would notice throttle response increases because you have more air readily available but the pressure is lower.

If you change the intake to become more free flowing or add FI, a larger throttle body may result in horsepower gains, but you have to really treat it as just an extension of the intake manifold.

It's actually similar to wha we do in paintball with high pressure low volume vs low pressure high volume. If you have a valve chamber running 700 psi into it, that's 700 psi worth of force hitting the ball to propel it to 280 fps. Now assume you significantly increase the size of that valve chamber. You can store much more air there at a lower pressure and propel the ball to the same speed with much less force.
I think the standard formula is p1v1 = p2v2.
blah blah blah..

mspeed11

your only as fast as your slowest link. this is true in everything! :D

rotarygod

It's a good thing the weakest link on this engine isn't the intake manifold or throttlebody.

shelleys_man_06

From thermodynamics, assuming steady-state, I don't think you would be able to get any power, as the enthalpy going in is equal to enthalpy going out for a throttling process. I think you can get a change in power as the throttle opens with time (more mass flow rate).

Nemesis8

iTrader: (3)

Will the "fly by wire" control stop everyone from modifying the body? Or am I just confused?

Richard Paul

iTrader: (5)

To everyone except RG. WHAT THE HELL ARE YOU TALKING ABOUT????

zmzmrx8

So a polish would give better throttle response? If so this seems like a avenue to explore.
Just my opinion.

rotarygod

A polish will do nothing useful. It is already pretty smooth. Making it shiny won't help. The only thing that would make a difference would be to make it larger. Then you run into a host of other problems though. Just leave it alone. There is nothing to be had there.

Richard Paul

iTrader: (5)

AMEN.
RG answer your PM

shelleys_man_06

That's what I said, but in thermo II terms.

zoom44

they are talking about "porting and polishing" the throttle body opening in order to gain more or better airflow. basically boring a larger smoother path thru the throttle body. but since it alreadys flows as much air as the intake manifold can handle there's no point. but you already knew that and were perhaps wondering what deep end they fell off of?

shelleys_man_06

Haha. I think Richard was referring to me.

I found the thread about throttle bodies I talked with bgreene about.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/throttle-bodies-34579/

Richard Paul

iTrader: (5)

Nope, it's Ajax that went off the deep end.

Ajax

Lol, alcohol and cars will do that to ya.

Am I wrong that increasing the available volume (by boring out or replacing the throttle body) would change the overall air pressure inside the throttle body?

More space, same amount of air flowing in = less pressure.

Richard Paul

iTrader: (5)

Think about it. OOps that's what you were doing. And that's agood thing, keep thinking. But you increase the area of the t body so you get a volume increase equal to the increase times the amount of t body on the manifold side. Which is nothing compared to the plenum size.

Next the air is always moving and when you figure the feet per second you will find the decrease from boring the t body to be so small that it has no effect. Now if you replace the t body with one a lot bigger the air really slows down and it hurts the response unless you have increases the airflow of the engine somehow like FI.

I'll see if I can find you some formula that I once wrote up to show basic math for engine builders.

Ajax

Right, like i said above, it's useless unless you increase the rate at which you flow air into the throttle body unless the intake is being limited by the throttle body as it is. If you increase that rate (cfm), you increase the volume of air available immediately to the engine inside the throttle body. I realize it was probably pretty cryptic, but i was intoxicated :b

rotarygod

If your intake manifold runners and engine ports can't flow as much air as the throttlebody can, there isn't much point in making it larger. It won't help. The throttlebody is not a restriction in the system. The engine will only flow as good as the weakest point in the entire system. It doesn't matter if that restictin is before, at, or after the throttlebody. In the case if the Renesis, the restriction is in the engine itself not the manifold system.

Richard Paul

iTrader: (5)

Here is the formula:

A= cfm over 60 over feet per sec

CFM = A x fps x 60

A= area
FPS= feet per sec

i can't get it to take the whole set of formula, it would be usfull.